Conventional incandescent light sources generally convert an electrical current to light by applying a current to a filament, typically made of tungsten, which causes the filament to glow. The filament is generally suspended near the center of a glass bulb, thereby providing radial distribution of light that can be used to illuminate, e.g., a room. Such conventional incandescent light sources are typically used in chandeliers. Due to the high brightness of the glowing filament (˜1 Mcd/m2), crystals in the chandelier exhibit decorative sparkling light effects. However, the life span of incandescent light sources is typically relatively short, usually limited to the life span of the filament. In addition, the glass bulb generally becomes very hot due to the high temperature of the filament, presenting a potential danger of burning objects that come into contact with the glass bulb.
Replacing incandescent light sources with LED light sources generally alleviates or eliminates the above problems. In addition, such a replacement provides a significant increase in the efficacy, that is the luminous flux produced by the light source as a ratio to the amount of energy (or power) required to produce it. However, most LEDs are only capable of emitting light into a hemisphere (solid angle 2π sr), whereas incandescent light sources employing a glowing filament generally emit light uniformly into a full sphere (solid angle 4π sr).
EP1610054A2 describes a LED lamp assembly for use with automobiles, the LED lamp assembly having a central optical light guide for conducting light emitted by a plurality of LED light sources to a deflector for projection sideways at an angle to the axis of the light guide.